Alkalinity

Discussion in 'Reef Chemistry by Randy Holmes-Farley' started by Neo Jeo, Mar 8, 2018.

  1. Neo Jeo

    Neo Jeo Well-Known Member

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    I’ve had my tank up and running for about a month and for some reason my alkalinity is around 6.7-7.2

    I have done three water changes so far . I use coralife salt. Why isn’t it in the 8 to 11 area ?
     
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  2. saltyfilmfolks

    saltyfilmfolks Lights! Camera! Reef! R2R Supporter R2R Excellence Award Reef Squad Leader Photo of the Month Award Build Thread Contributor

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    What size tank? What size water changes? What test kit?
     
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  3. Crabs Mcjones

    Crabs Mcjones Tank Mechanic R2R Supporter R2R Excellence Award Reef Squad Leader Reef Tank 365 Article Contributor Build Thread Contributor Partner Member 2018

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    When you mix up saltwater how long are you letting it sit before using it?
     
  4. Neo Jeo

    Neo Jeo Well-Known Member

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    120G
    18% water change
    Hanna test kit

    Maybe the Hanna? Maybe I’m doing it wrong?
     
  5. Neo Jeo

    Neo Jeo Well-Known Member

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    2 days
     
  6. lewisriverfisherman

    lewisriverfisherman Member

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    I would test the salt that you mix up and see what you get? If it's low you might have to dose Alk.
     
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  7. Neo Jeo

    Neo Jeo Well-Known Member

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    Ok, I checked how I’m testing and I’m doing it right. I don’t have that many corals so I don’t understand why it’s low.
     
  8. mystersyster

    mystersyster Member

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    6.7 to 7.2 is fine as long as it's stable. What is your salinty? Do you have a lot of sps and lps?
     
  9. Crabs Mcjones

    Crabs Mcjones Tank Mechanic R2R Supporter R2R Excellence Award Reef Squad Leader Reef Tank 365 Article Contributor Build Thread Contributor Partner Member 2018

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    Do you notice any precipitation after two days? Are you heating and mixing the water or is it just sitting.
     
  10. Neo Jeo

    Neo Jeo Well-Known Member

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    I thought 8-11 is normal range. My salt lvl is 1.026 . I have a few corals nothing much, I just started
     
  11. Neo Jeo

    Neo Jeo Well-Known Member

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    I’m heating it and mixing. With a lid on.
     
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  12. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Article Contributor Expert Contributor

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  13. Neo Jeo

    Neo Jeo Well-Known Member

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    Well it looks like I have some reading to do then
     
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  14. Neo Jeo

    Neo Jeo Well-Known Member

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  15. Oberst Oswald

    Oberst Oswald Active Member

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    Don't put your complete trust in the Hanna reagents. I once bought 3 new bottles and did a test with the 3 of them. Two were close but one was far enough off from the other two that I always worry when I get my next new bottle it will show my alk is not what it was.
     
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  16. rkpetersen

    rkpetersen Lesser-Known Randy R2R Supporter R2R Excellence Award Partner Member 2018

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    OP, first check your freshly made salt to see what alk is actually going in. If it's on the low side, consider changing salt to something like Red Sea Coral Pro, which consistently mixes up to an alk of 10+. Second, if your alk is lower than the salt you're using and you have few stony corals and clams, the decreased alk in your system is probably due to some undetected abiotic precipitation of calcium carbonate. It can encrust on heaters, pumps, and other warm surfaces. Third, if this is the case, you should consider manual or even better automated 2 part dosing. Or, if you use an auto top off system you could consider trying kalkwasser, although it warrants some respect as it can kill your tank if an accident occurs.
     
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  17. Crabs Mcjones

    Crabs Mcjones Tank Mechanic R2R Supporter R2R Excellence Award Reef Squad Leader Reef Tank 365 Article Contributor Build Thread Contributor Partner Member 2018

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    I would start with checking your saltwater right after you've mixed it as others have said. But I generdally don't let me salt mix sit (even if it has a powerhead and heater) for more than 2 hours.
     
  18. NS Mike D

    NS Mike D Active Member R2R Supporter Build Thread Contributor

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    some salt directions say to mix the salt for 24 hours before adding to the tank. can you elaborate on this? when I buy salt water from the LFS I presume it was made in advance, day and weeks - are you suggesting this is inferior salt water?
     
  19. Randy Holmes-Farley

    Randy Holmes-Farley Reef Chemist Staff Member Team R2R R2R Supporter R2R Excellence Award Article Contributor Expert Contributor

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    The concern is that the alkalinity is very high in some salt mixes, and the tendency for abiotic precipitation of calcium carbonate is much higher in raw salt water than in an aquarium. So people often see the alkalinity decline over time, especially if they heat it or mix it with a powerhead that is getting water (calcium carbonate is less soluble at higher temps).

    Some people do not see this problem at all, or they do not care as much. Your home air Cow levels alters the pH of the aerated salt water, and pH is a big driver of potential precipitation.

    I store my new salt water for a month and used it just fine, but I also wasn't particularly focused on ensuring the alkalinity in it was exactly the same every day.
     
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  20. cracker

    cracker Valuable Member R2R Supporter R2R Excellence Award Build Thread Contributor

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    I think the 24 hrs mix is for aerating the water . My Alk always drops if left in the barrel for a while like a day or 2 .
     
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